Liquid level indicator

Abstract

A liquid level gauge having a body defining a liquid receiving chamber, a transparent reflex glass at an open face of the body chamber for maintaining liquid within the chamber while providing visual access into the chamber, a removable cover plate maintaining the reflex glass in sealing engagement with the chamber body, the reflex glass including on its inner face a plurality of longitudinally extending prisms adapted to be contacted by liquid in the chamber, a background plate within the walls of the chamber, and means to space the background plate from the reflex body to permit circulation of liquid therebetween, the background plate displaying through the reflex glass a high visual contrast, e.g., a bright color, between wetted and nonwetted areas of the reflex glass. As disclosed, the reflex glass may be formed of a transparent plastic material and be arranged with a relatively thin cross section to permit its use as an insert for assembly with an outwardly disposed primary pressure-retaining glass.

What is claimed is: 
     
       1. A reflex glass assembly for a liquid level gauge comprising an elongated, transparent body, an inner face of said body having a plurality of parallel, longitudinally extending reflex prisms, a background element spaced inwardly of said inner body face, said background element displaying a high visual contrast to the characteristic reflex appearance of the reflex body at a nonwetted area thereof, and means extending between said background element and said body and supporting said background element on said reflex body, said background element support means being adapted to be disposed within a liquid-containing chamber and being adapted to support said background element independently of said chamber. 
     
     
       2. A reflex glass assembly as set forth in claim 1, wherein said background element is an elongated member and said support means maintains said background element in spaced parallel relation to said reflex body. 
     
     
       3. A reflex glass assembly as set forth in claim 1, wherein said reflex prisms extend transversely and longitudinally across a central area of said body, said background element having a transverse width slightly less than the transverse extend of said central prism area to provide limited side clearance of said background element in a liquid-containing chamber sealed and visually revealed by said reflex body. 
     
     
       4. A reflex glass assembly as set forth in claim 1, wherein said transparent body is clear and wherein said background element is arranged to provide said high visual contrast by displaying a bright color contrast with a characteristic silver-white reflex appearance of said body. 
     
     
       5. A reflex glass assembly as set forth in claim 1, wherein said support means is integral with one or both of said reflex body and background element members. 
     
     
       6. A reflex glass assembly as set forth in claim 5, wherein said support means includes a support member adjacent each end of said background element. 
     
     
       7. A reflex glass assembly as set forth in claim 6, wherein each end adjacent support member has a cross sectional area in a plane transverse to the longitudinal direction of said reflex body less than the area between said background element and said reflex body described by the lateral extent of the background element, whereby the liquid flow between said background element and reflex body is substantially unimpeded. 
     
     
       8. An insert for a liquid level gauge comprising a reflex body, a background element and means supporting the background element on the reflex body, said reflex body being formed of a rigid, clear, transparent plastic material and including an elongated planar base portion, said base portion having rounded ends and a substantially planar outer surface adapted to abuttingly engage a planar face of a primary pressure-retaining gauge glass, a plurality of longitudinally extending prisms integrally formed with their roots on the rear face of said base portion and projecting rearwardly therefrom, said base portion including a rearwardly facing planar sealing surface completely surrounding said prisms both laterally and endwise and adapted to seal a chamber in which liquid is observed through said insert, the height of said prisms being at least in the order of the thickness of the base portion between said inner and outer planes, the total thickness of said reflex body, formed by the combined thickness of said base portion and the height of said prisms, being substantially less than the width of said base portion, said background element being a generally planar structure having a length substantially as long as said prisms and a width somewhat less than the transverse field of the prisms whereby said background element affords limited lateral clearance in the chamber of liquid being observed, said support means including means projecting between said reflex body and said background element at each end thereof, said projecting means being integrally formed with at least one of said reflex body or background element members and being fixed to the other, said projecting means supporting said background element is spaced, parallel relation to said reflex body.